This invention relates to an apparatus and method for shaping an article from moldable material in a mold opening in which the material is forced into the opening while the displaced air is vented in a free flow path from the opening to the exterior after which the air vent is closed and then the supply of material to the mold opening is terminated while maintaining molding pressure of the material. Then the opening is moved out of conjunction with the material supply with both valves remaining closed until the mold opening with the contained article has reached an article ejecting position.
With the apparatus and method of this invention the power requirements for charging the mold opening with the material being molded are greatly reduced because there is very little back pressure from the mold opening on the material entering the opening. Most of the back pressure in devices of this nature is caused by entrapped air which not only increases the power requirements in compressing this air but also results in extraneous air being trapped with the material within the opening. This not only increases greatly the power requirements to make a desirably shaped article but also often results in misshapen articles because of the entrapped air.
With the apparatus and method of this invention the mold is sealed to the supply passage for the material on the side of the mold opposite the air vent and seal so that there is substantially no loss of any liquid components from the pressurized material.